A contactor is an electrically controlled switch used for switching an electrical circuit. An electromagnet is used for closing the electrical circuit by forcing a moving contact into electrical contact with a stationary contact. Energy for the closing operation is typically transferred from an electromagnet to the moving contact by a mechanical mechanism. The mechanism could either have a direct connection or a fixed gear ratio. The moving and stationary contacts may be worn and their electrical lifetimes may be reduced by the moving contact meeting the stationary contact with high speed and contact bounces may be created, which may give rise to arcs that reduces the electrical lifetime.
To have a variable speed on a transferring mechanism is shown in documents US 2011/0155555, U.S. Pat. No. 5,541,378, U.S. Pat. No. 3,992,600 and CN 101702388, which documents disclose how to dampen the closing of a switch. The solution according to US 2011/0155555 is to use a sliding element with different slopes. In U.S. Pat. No. 5,541,378, a drive device based on a cam disk with a curved path is used. In U.S. Pat. No. 3,992,600, a rod with a lever and a second mass are used in order to affect the speed of the switch and in CN 101702388 which is used in an arc extinguishing chamber, connecting rods are movable in a curved path. These disclosures represent alternative solutions, each with its own advantages and disadvantages.